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Isotopic evidence for the provenance and turnover of organic carbon by soil microorganisms in the Antarctic dry valleys
Author(s) -
Hopkins D. W.,
Sparrow A. D.,
Gregorich E. G.,
Elberling B.,
Novis P.,
Fraser F.,
Scrimgeour C.,
Dennis P. G.,
MeierAugenstein W.,
Greenfield L. G.
Publication year - 2009
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2008.01830.x
Subject(s) - organic matter , soil water , environmental chemistry , biogeochemical cycle , detritus , soil organic matter , total organic carbon , environmental science , ecosystem , microorganism , ecology , biology , soil science , chemistry , genetics , bacteria
Summary The extremely cold and arid Antarctic dry valleys are one of the most environmentally harsh terrestrial ecosystems supporting organisms in which the biogeochemical transformations of carbon are exclusively driven by microorganisms. The natural abundance of 13 C and 15 N in source organic materials and soils have been examined to obtain evidence for the provenance of the soil organic matter and the C loss as CO 2 during extended incubation (approximately 1200 days at 10°C under moist conditions) has been used to determine the potential decay of soil organic C. The organic matter in soils remote from sources of liquid water or where lacustrine productivity was low had isotope signatures characteristic of endolithic (lichen) sources, whereas at more sheltered and productive sites, the organic matter in the soils that was a mixture mainly lacustrine detritus and moss‐derived organic matter. Soil organic C declined by up to 42% during extended incubation under laboratory conditions (equivalent to 50–73 years in the field on a thermal time basis), indicating relatively fast turnover, consistent with previous studies indicating mean residence times for soil organic C in dry valley soils in the range 52–123 years and also with recent inputs of relatively labile source materials.